feat: add chat for backend

internal/economy/handler.go

@@ -87,6 +87,49 @@ func (h *Handler) BuyCard(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// ChatPacks — GET /api/chat-packs (بسته‌های پیام/شکلک + مالکیتِ کاربر)
+func (h *Handler) ChatPacks(w http.ResponseWriter, r *http.Request) {
+	id, ok := uid(r)
+	if !ok {
+		httpx.Error(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	packs, err := h.svc.ChatPacks(r.Context(), id)
+	if err != nil {
+		httpx.Error(w, http.StatusInternalServerError, "server error")
+		return
+	}
+	httpx.JSON(w, http.StatusOK, map[string]any{"packs": packs})
+}
+
+// BuyChatPack — POST /api/shop/buy-chat-pack
+func (h *Handler) BuyChatPack(w http.ResponseWriter, r *http.Request) {
+	id, ok := uid(r)
+	if !ok {
+		httpx.Error(w, http.StatusUnauthorized, "unauthorized")
+		return
+	}
+	var req struct {
+		PackID string `json:"pack_id"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		httpx.Error(w, http.StatusBadRequest, "invalid body")
+		return
+	}
+	switch err := h.svc.BuyChatPack(r.Context(), id, req.PackID); {
+	case err == nil:
+		httpx.JSON(w, http.StatusOK, map[string]string{"message": "ok"})
+	case errors.Is(err, ErrNotFound):
+		httpx.Error(w, http.StatusNotFound, "pack not found")
+	case errors.Is(err, ErrAlreadyOwned):
+		httpx.Error(w, http.StatusConflict, "already owned")
+	case errors.Is(err, ErrInsufficient):
+		httpx.Error(w, http.StatusPaymentRequired, "insufficient coins")
+	default:
+		httpx.Error(w, http.StatusInternalServerError, "server error")
+	}
+}
+
 // SelectCard — POST /api/shop/select-card
 func (h *Handler) SelectCard(w http.ResponseWriter, r *http.Request) {
 	id, ok := uid(r)